Air driven turbines



Aug. 28, 1962 w. CHANDLER 43,051,44Q

AIR DRIVEN TURBINES Filed July 20. 1960 United States Patent 3,051,440 AIR DRIVEN TURBINES Robert Walter Chandler, Solihull, England, assignor to Rotax Limited, London, England Filed July 20, 1960, Ser. No. 44,179 Claims priority, application Great Britain July 27, 1959 1 Claim. (Cl. 25377) This invention relates to air driven turbines more particularly for use on aircraft, and of the kind having a rotor comprising a central body part carrying a plurality of equi-angularly spaced peripheral blades.

In the event of a blade of such a turbine rotor becoming detached, or being broken away, the dynamic balance of the rotor is upset with the result that there is a grave risk of the rotor as a whole breaking up if it continues to rotate at high speeds. Such breaking up of the rotor may have very serious consequences, more particularly when the turbine is mounted in an aircraft, and the object of the present invention is to provide a turbine rotor in a convenient form whereby the breaking away or detachment of a rotor blade will ensure release of the other rotor blades to restore the dynamic balance of the rotor, and cause the body part of the rotor to slow down.

According to the invention, in a rotor for an air driven turbine of the kind specified the blades are freely located relative to the central body part and are held in position by means of an encircling member which is locally weakened at at least one angular position.

An example of the invention is illustrated in part-sectional side elevation in the accompanying drawing.

Referring to the drawing, the rotor comprises a central body part a which is dynamically balanced and has in its peripheral portion a plurality of equi-angularly spaced recesses or holes for the reception of pairs of dowels or similar projections b on the turbine blades 0, each blade having a pair of the dowels or similar projections secured thereto so as to extend therefrom in parallel relationship with each other into axially slidable engagement with the corresponding recess or holes in the peripheral portion of the central body part.

Encircling the blades 0 is an endless band d which serves to retain the dowels or similar projections b of the blades within their locations in the body part a. The arrangement is such that the pairs of dowels or like projections b serve to locate the blades 0 against angular movement relative to the body part, but the sole means restraining the blades from radial disengagement from the body is the encircling band d. The latter is locally weakened, as by holes, at at least one, but preferably as shown three equi-angularly spaced positions 2, and is designed to P 1 cc break under the centrifugal forces due to its own weight and that of the blades c which it retains when the turbine is rotated at a predetermined speed above its normal operating speeds. In the event of the band at being broken when the rotor is rotating all the blades will be thrown from the body part by centrifugal forces thus restoring the dynamic balance of the rotor. Moreover, as soon as the blades of the rotor are detached the rotor will start to slow down since there are no suitably shaped parts on which the air jets can react to impart the rotation. Conveniently, some of the dowels or like parts b extend through their associated blades into holes or recesses on the band as shown at b1 so as to locate the band d against axial movement.

It has been found in experiments that the detached blades and/ or broken parts of the band can pass from the turbine exhaust without serious damage such as is likely to occur in the event of the body part of the rotor breaking up.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

A rotor for an air-driven turbine of the kind specified, comprising in combination a central body part, a plurality of blades extending in equi-angularly spaced relationship from the periphery of said body part, projections rigid with said blades and extending therefrom into axially slidable engagement with openings in the peripheral portion of said body part, and an endless band which encircles said blades to hold them in position on said body part, and which has at least one weakened portion for enabling said band to be broken by centrifugal forces, due to the weight of said band and blades, in the event of the rotor exceeding its normal maximum speed by a predetermined amount.

References Cited in the file of this patent UNITED STATES PATENTS 1,469,045 MacMurchy Sept. 25, 1923 1,634,897 Davis July 5, 1927 2,310,412 Flanders Feb. 9, 1943 2,349,187 Meyer May 16, 1944 2,942,843 Sampson June 28, 1960 2,965,355 Spaeth Dec. 20, 1960 FOREIGN PATENTS 342,900 Germany Oct. 26, 1921 405,301 Italy Feb. 19, 1942 532,372 Great Britain Ian. 22, 1941 537,455 Great Britain June 23, 1941 837,495 Germany Apr. 28, 1952 1,223,925 France Feb. 1, 1960 

